How to get the unique items out of a list in Google Apps Script?

June 15, 2022

I have this code snippet:

function getTimeFrames(){
  var ss = SpreadsheetApp.getActive();
  var cell = ss.getRange("C1").getValue();
  Logger.log(cell);
  
  var s = ss.getSheetByName(cell).getRange("M2:M");
  var unique = new Set(s.getValues());
  
  unique.forEach(x => Logger.log(x))
}

This code would be called from a Google Sheets spreadsheet which serves as an UI, where the C1 cell would be a name of a sheet used for storing data. In that sheet I have a column (M) that I need to get the unique values out of in order to store in a drop-down in the UI sheet.

The problem I have is that I can’t get the unique values part working at all. Throughout my experimentation, I would either get a list of all the values of column M or no Logging output at all.

Any help is greatly appreciated!

>Solution :

Try

function getTimeFrames(){
  var ss = SpreadsheetApp.getActive();
  var cell = ss.getRange("C1").getValue();
  Logger.log(cell);
  
  var unique = ss.getSheetByName(cell).getRange("M2:M").getValues().flat().filter(onlyUnique)

  console.log(unique)
}
function onlyUnique(value, index, self) {
  return self.indexOf(value) === index;
}